1. Field of the Invention
The present invention relates to a medical laser apparatus which is used in an ophthalmic hospital and others.
2. Description of Related Art
As medical laser apparatuses (e.g., for ophthalmic treatments), there have been known apparatus using a krypton laser, a dye laser, a frequency doubled Nd:YAG laser which is a solid laser, or the like. For example, the krypton laser can generate green laser beams of wavelengths of approx. 520 nm and approx. 530 nm, a yellow laser beam of a wavelength of approx. 568 nm, and a red laser beam of a wavelength of approx. 647 nm. The dye laser can generate yellow to red laser beams of wavelengths of approx. 575 nm to approx. 630 nm. The frequency doubled Nd:YAG laser can generate second harmonics, that is, a green laser beam of a wavelength of approx. 532 nm, a yellow laser beam of a wavelength of approx. 561 nm, and a red laser beam of a wavelength of approx, 659 nm.
For medical treatments, a laser beam of a wavelength (namely, color) selected according to a treatment part, a treatment purpose, and others is used. For an ophthalmic photocoagulation treatment, for example, yellow to orange laser beams are preferably used for providing a good coagulation efficiency even at low energy. In the case where a patient's eye is bleeding at the fundus or an optic media to the fundus is opaque, a red laser beam is preferably used.
The apparatuses using the krypton laser or the dye laser have many disadvantages; a short life of a laser tube, large electric power requirements, and an increase in apparatus size. On the other hand, the apparatuses using the solid laser such as the frequency doubled Nd:YAG laser could reduce these disadvantages but could not generate an orange laser beam suitable for photocoagulation. Further, as the red laser beam, a beam of a wavelength shorter than approx. 659 nm is preferable.